As the title said, why I could not attach a 50 MB file even though MXroute support up to 50 MB of messages size?
You could read the details on here: http://ask-leo.com/why_are_emailed_attachments_larger_than_the_original_file.html
According to the article, email is an old technology and it primarily were text-only media. So if we attach a file, which is basically a binary data, it will be encoded into text file which will increase the file size by 37%.
If the maximum message size supported in MXroute is 50 MB, then the maximum file you could attach in an email would be around 36 MB.
36 MB + ( 37% x 36 MB) = 49.32 MB
But not all email provider accept a 50 MB email size, Google accept incoming mail of 50 MB, but Microsoft/Outlook only accept 36 MB email size (25 MB file attachment).
That calculation can vary a bit too based on the file and type.
Of course, Jar
I use .zip attachment as example on above calculation.